Preservation of electronic equipment during earthquakes and aftershocks for the maintenance of communications and other purposes is a major concern of earthquake preparedness. Indeed, alleviation of damage and suffering depends to a large extent on the maintenance of the telephone system and broadcast facilities, to name two examples.
With the introduction of electronic and fiber optic telephone switching equipment, the density of calls being handled in one equipment rack or network bay has advanced significantly. Today as many as 20,000 telephone lines could be interrupted with the loss of one bay of equipment. This has made the reliability cf telephone switch equipment and its supporting structure critically important. Concern for earthquake protection of this equipment has become very important.
Several approaches to solving these problems were tried. It may be possible to make an equipment rack or network bay that is strong enough to avoid earthquake damage by using heavier material and more bracing members, but this adds significantly to the cost. This would no longer be compatible with the competitive environment of modern telephone systems. Moreover, spot-welding and similar measures have not imparted sufficient earthquake resistance to prior-art types of equipment racks.